Vrm data section, Rail group summary section – Altera Device-Specific Power Delivery Network User Manual
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The available options are:
• " " — Device rail does not connect to the power group.
• x — Device rail connects to the power group.
• x/related— Device rail connects to the group, and its activity is related to other rails that connect to
the same group. You must select x/related if that VCCIO/VCCPT power rail is related to other rails
within the same power rail group.
Note: Two IO rails are related if their output activities are synchronous. For example, when two
VCCIO rails are assigned to the same memory interface. The maximum current will usually be
reached at the same time for these related rails. As a result, the total current of related rails
equals the sum of the current of all shared rails. The total current of unrelated rails is calculated
using the root-mean-square (RMS) method.
The PDN tool 2.0 sets the default power rail sharing configuration based on the selected Altera-
recommended power rail configuration listed above. Make changes to better match your design.
Related Information
VRM Data Section
Enter the voltage regulator module (VRM) parameters for DC supply voltage at Switcher VRM
Efficiency and Switcher VRM Input Current.
Rail Group Summary Section
In this section, you can find a list of the following calculated key parameters of all power groups:
• Voltage
• Total Current
• Dynamic Current Change
• Die Noise Tolerance
• Core Clock Frequency
• Current Ramp Up Period
• Z
TARGET
These options allow you to customize how the data is collected or analyzed.
The Dynamic Current Change parameter has a pull-down menu with the following options:
• Calculate
• Override
Dynamic current change percentage requires a lot of diligence. The EPE and PPPA both deliver values for
current usage that include:
• the maximum static current (does not vary)
• the maximum current usage by the active elements
This calculation yields both a very high total current and a fairly high dynamic current usage. Calculations
for a value to insert into the Dynamic Current Change field could yield a value much lower than the
auto-populated value, which represents a safe engineering value.
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VRM Data Section
UG-01157
2015.03.06
Altera Corporation
Device-Specific Power Delivery Network (PDN) Tool 2.0 User Guide